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3 years ago

13

A collection of quarters and dimes is worth $12.40. There are 67 coins in all.

1 answer:

padilas [110]3 years ago

5 0

Let:
x= quarters
y= dimes

x+y=67
and
.25x+.10y=12.40

x=67-y

.25(67-y)+.10y=12.40
16.75-.25y+10y=12.40
16.75-.15y=12.40
Lets rearrange this:
-.15y+16.75=12.40
-16.75 -16.75
-.15y=-4.35
the negatives cancel out
.<u>15y</u>=<u>4.35
</u>.15<em /><em> <u /></em>.15
y=29

Back to the original x=67-y
x=67-29
x=38

So,
x=38
y=29
<em />

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